1. Field of the Invention
It is important to seal rotating shafts to prevent lubricants associated with the bearings from leaking from the bearing housing and also to prevent contaminants in the environment from proceeding into the lubricant of the bearings.
2. Related Art
Labyrinth seals are described in U.S. Pat. No. 4,706,968 and the prior art cited therein. These seals have labyrinths between a plurality of rings where at least one ring is stationary and one of the ring rotates with the shaft. U.S. Pat. Nos. 4,706,968 and 5,174,583 provide for a third ring member to improve the sealing action of the labyrinth interfaces and to allow for some axial separation of the fixed or stationary ring and the rotating ring while still maintaining a seal. These seals have resolved a great number of the problems related to sealing during axial shaft displacement, however, there continues to be problems in maintaining adequate sealing over a period of time using seals associated with axial shaft displacement. These sealing units are most generally required to accommodate a shaft that simultaneously moves axially and rotatively. This movement occurs with sleeve bearing motors and with long shafts wherein one of the ends of the shaft is tied by means of a fixed bearing and the opposite end is allowed to float.
Previously, the stators and rotors of the bearing isolators were locked together to prevent this axial separation. The axial thrust which occurs between the rotating member and the fixed ring member must be absorbed by the axial faces of the stator and rotor. This thrust and axial shifting sometimes damages bearing isolators which were locked together either by a separate internal locking device or when the bearing isolators were designed with interlocking features as an integral part of their design, such as in U.S. Pat. No. 5,174,583.
This invention is designed to alleviate these destructive thrust forces occurring on the faces of the rotor and stator due to frictional engagement between the rotating member and the stationary member when the shaft moves axially.